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' F. B, MILLER MECHANICAL HAMMER roct. 19, 1937.

original Filed May 16, 1935 2 *Sheets-Sheet l 7 www www, Nimm.

Oct. 19, 1937. F. B. MILLER MECHANICAL HAMMER Original Filed May 16, 1935 2 Sheets-Sheet 2 FEEDER/CK B. M/LLEE y www QM h @ifo/Ways.

Reissued Oct. 19, 1937 PATENT orgies MECHANICAL HAMMER Frederick B. Miller, Chicago, Ill.v

Original No. 2,017,470, dated October 15, 1935, Se*

rial No. 21,879, May 16, 1935.

Application for reissue February 17, 1937, Serial No. 126,204

11 Claims.

The invention relatesto mechanical hammers, or what are known as picking bars, such as are used in mining operations and the like.

One of the most popular types of mechanical hammers, or picking bars, employs a housing, a resiliently mounted tool, `such as a chisel, and a resiliently mounted he1ve which is driven through a cam to deliver'rapid impacts, or impulses, tofthe tool. Considerable diiculty has beenV experienced in using devices of this type due lto the fact that the velocity of the helve, imparted by the cam, controls its limit, 'or throw. The cam must be constantly rotated at a uniform speed, otherwise the throw of the helve will not 15, be uniform'and will result in the striking of the tool shank when itis in its forward position. This necessary uniform speed of cam rotation is extremely diiiicult to maintain.

Itis one of the objects of the present invention to provide a mechanical hammer employing a helve whoseV throw is limited independently of the speed o'f' rotation of the cam by which it is operated. l

f `Another'cbject is to provide a novel mechanical hammer employing a system of springs which operate to Yabsorb unspent forces of the helve, thus assisting its return, and the consequent release from the helve spring of that amount of pressure, cr energy, which is absorbed therein. 30. ThisV manner of operation conserves energy required for the reciprocation of the fhelve by its operating cam,

In accordance with the teaching of the present invention, the impetus lent the helve is augmented to vcreate av throw which is Vgreater than that of the cam, the length of which is dependent upon theV speed of rotation of the latter. j

Another object is to provide a novel device of the class described which may be easily and cheaply manufactured, and one which at the same time will prove very durable in service.

These and further objects will be apparent after referringto the accompanying drawings, in which: Y

Figure 1 is an4 elevation of the dev-ice of the invention shown partly in section; e

Figure 2 is a viewsimilar to Figure 1 but disclosing the various elements in another stage of 50 operation;

Figure 3 is an enlarged fragmentary sectionalV 5 in Figure 3;

Figure 5 is a view similar to Figure 2 but disclosing the various elements in another stage of operation;

Figure 6 is a modification.

Referring more particularly to the drawings, the numeral 2 designates a substantially cylindrical housing for the Various elements of the device of the invention which is provided on one of its ends with a reduced portion 3, while on the other end thereof is disposed the usual yoke 4, and handle 5, for enabling its easy handling by a workman.

The housing 2 is provided on its interior surface relatively adjacent its end having the reduced portion 3, with an inwardly extending flange E, which is centrally apertured, as at 8. This inwardly extending flange 5 provides within the housing 2 a relatively short cylindrical chamber Si, which is partially closed on its end nearest the reduced portion 3 by aninwardly extending flange Il). Between the flange I ii and the reduced'end 3 of the housing 2, the latter is provided with a relatively narrow annular groove I2, which terminates in a shoulder I3. A recess I4 of relatively small` diameter opens on this shoulder I3 and terminates in a flange I5, which is centrally apertured, as at I6.

The tool shaft of the novel mechanicall hammer of the invention is generally indicated as at I8, and is slidably mounted in the apertures 8 and I6 or the anges and I5, respectively. The extremity of the tool shaft i8 which protrudes from the housing 2 is provided Withrthe usual cutting edge I9, or other medium, for promoting its effectiveness upon that which it is intended to operate. The substantial mid-portion of the tool shaft I8 is provided with an annular ange 20, and an adjoining retainer flange 2l of greater diameter. A coil spring 23 is disposed in the chamber 9 around the tool shaft I8 and in contact with the retainer flange 2I on thelatter and the flange 6 `of the housing 2.

The annular flange 2% serves to maintain the coil spring 23 against lateral movement on the tool shaft I8. Afiange 24 is provided on the tool shaft I8 adjacent the retainer iiange 2| and on the side of the latter which is opposite the annular flange 2i). This iiange 24 is of substantially the samediameter as that of the opening provided by the inwardly extending iange ID of the housing 2. A' coil spring 25 is disposed in the annular groove I2 and adapted to make contact on one of its ends with the adjacent side of the flange 24 and on its other end with the shoulder I3 on. which the recess I4 opens.

IIhe tool shaft I8 is provided on its end adjacent the flange 6 with a stop-flange 26 for preventing its excessive movement through the aperture 8.

The housing 2 is reduced in internal diameter adjacent the flange 6 and provided with an inwardly extending annular flange 21 to form a cylindrical chamber 28. The end of the substantially cylindrical housing 2 whichl is opposite the reduced end 3 is open, as shown at 29, and

and the flange 21.

A sleeve 3| is disposed for slidable movementv in the elongated cylinder 30 in the housing 2. This sleeve 3| .is provided on its end which is most adjacent the flange 21 with an inwardly extending annular ange 33. The other end of the sleeve 3| is closed, as at 34, and carries a frame 35 which has a substantial lateral opening 35 therein. A pair of bearing shoes 31 are disposed on diametrically opposite sides of the opening 36 in the frame 35 in the plane of the axis of the sleeve 3|. A reciproca-ble shaft 38 is disposed to extend through the opening 36 in the frame 35 and carries an eccentrically mounted disk 39 which is adapted to constantly make contact with the shoes 31.

The shaft 38 is driven at a relatively high speed in any suitable manner in accordance with the teaching of the prior art.

A shaft 4| is slidably mounted in the aperture formed by the inwardly extending flange 33 on the sleeve 3| and is provided on its substantial mid-portion with an annular flange 42 and an adjacent relatively elongated cylindrical boss 43 of slightly smaller diameter. The shaft 4| is also provided with a flange 44 on the side of the elongated cylinder 43 which is opposite the flange 42. This shaft 4| in the sleeve 3| carries a coil spring 45 which makes contact on one of its ends with the adjacent side of the inwardly extending flange 33, while the other end thereof contacts the adjacent side of the elongated cylindrical boss 43. The annular flange 44 thus serves to center the coil spring 45.

- A coil spring 46 is carried by the shaft 4| on the opposite side of the elongated cylindrical boss 43 and is centered by an annular flange 41 on the latter and a. guide plug 48 on the adjacent side of the frame 35.

The end of the shaft 4| in the sleeve which is adjacent the inwardly extending flange 6 of the housing 2 is reduced in diameter as shown at 49, and made to extend into the cylindrical chamber 23. This reduced portion 49 of the shaft 4| provides a shoulder 50. A coil spring 5| is disposed in the cylindrical chamber 28 and maintained by means of a retaining washer 52 which contacts the adjacent side of the inwardly extending annular flange 21.

In operation the shaft 38 is constantly rotated with its eccentrically mounted disk 39 in contact with the shoes 31 in the frame 35, thus imparting reciprocation to the elongated sleeve 3|'. The shaft 4| is initially moved forwardly through the spring 46 in the sleeve 3|. This movement is, however, resisted by the spring 45 in the elongated sleeve 3| and also the spring 5| in the cylindrical chamber 28, which is compressed by the shoulder 50 formed by the reduced portion 49 of the shaft 4|. It is the function of the spring 23 in the housing 2 to absorb the initial thrust of the shaft I8 caused by maintaining the chisel I9 against the material to be worked upon. The shaft lll is struck by the shaft 4| and moved for-l wardly with it, being assisted by the spring 23. Ihere is not, however, sufcient thrust on the shaft |8 to compress the spring 23 suiciently to maintain the former in its extreme rearward position, or within the striking range of the shaft 4|. Thel shoulder 50, formed by the reduced end 49 of the shaft 4| contacts the retaining washer 52 in the cylindrical chamber 28 and compresses the spring 5|, thereby forming a yielding resistance that limits the throw of the shaft 4I with its elongated cylindrical boss 43 which, taken together, form the helve or hammer. The impetus lent the helve by the spring 4E creates a helve-throw greater than the cam-throw, the length of which is dependent on the speed of rotation of the cam. The uniform throw of the helve is usually dependent upon constant or uniform speed of the cam rotation which is difficult to maintain, due to the usual power fluctuations. Therefore, to keep the movement of the shaft |8 within certain limits it is desirable to limit the throw of the helve to prevent its being struck at such time when it is in its forward position.

By means of the resistance imparted by the coil spring 5| the throw of the helve is controlled without maintaining a constant or uniform speed of cam rotation. Furthermore, the resistance imparted by the coil spring 5| absorbs unspent forces of the helve which assists in returning it, thereby relieving the coil springs 45 and 46 of the amount of pressure or energy absorbed in the former. 'I'his also conserves the energy required for reciprocating the helve In Figure 6 of the drawings, I have disclosed a modified form of the device of the invention. According to this embodiment, the main portion of the housing is generally indicated at 65 as comprising a sleeve which carries on one of its ends an'extension 61 of reduced diameter. The outer end of the extension 61 is provided with an inwardly extending annular flange 68. A washer 69 is disposed between the housing 65 and the extension 61 and serves to retain a ring 1D which is disposed within the latter. A similar ring 1| is disposed in the extension 61 against the inwardly extending annular flange 68. These rings 69 and 1| are maintained in separated position by a coil spring 12. A shaft 13 extends through the extension 61 and carries a shoulder 14 which is constructed to contact the ring 1|. This shaft 13 is suitably retained and carries a tool (not shown).

A relatively shorter sleeve 15 is provided in the housing 65 of Figure 6 in lieu of the sleeve 3| in the housing 2 of Figures l through 5. This sleeve 15 is provided on its end adjacent the extension 61 with an inwardly extending annular flange 16. 'I'he helve of the embodiment of Figure 6 comprises a shaft 19 which has a cylindrical bore 8U in its end adjacent the frame 35. The opposite end of the shaft 19 reciprocates in the aperture provided by the inwardly extending annular flanger16, and is maintained in alignment therewith by an annular flange 8| on its end having the cylindrical bore 89 which is reciprocable within the housing 65.

A coil spring 82 is disposed within the sleeve 15 and around the shaft 19 This coil spring 82 makes contact on one of its ends with the inwardly extending annular flange 16 on the sleeve 15 and on its other end with the annular flange 8| on theV shaft 19. A coil spring 83 is disposed to extend into the cylindrical bore 80 in the shaft 19 with its end seating on the bottom thereof. The other end of the coil Spring 82 seats against the adjacent side, of the frame 35 and is maintained in position by the guide plug 48, all as in the embodiments of Figures l through 5.

The mode of operation ofthe modification of Figure 6 issubstantially the same asthat previously described. That is to say,the coil spring 12 in the extension 61 functions in the same manneras the coil spring 5| in the cylindrical chamber 28, While the springs B2 and 83 function in the same manner as the springs 45 and 4B. The remaining elements of both embodiments are identical, the sole purpose of the modication being to reduce the over-al1 length for operations within confined quarters.

While I have shown and described several specific embodiments of my invention, it will be understood that I do not Wish to be limited exactly thereto, since various modifications may be made without departing from the scope of my invention, as dened in the following claims.

What is claimed is:

1. A mechanical hammer comprising a housing, an operating shaft reciprocably mounted in said housing, said shaft beingY spring-pressed in opposite directions, a helve reciprocably mounted in said housing and in alignment with said operating shaft, said helve being spring-pressed in opposite directions and constructed and arranged to contact the adjacent end of the said operating shaft, means for reciprocating said helve, and resilient means backed by said housing and providing yielding resistance for decelerating the movement of the helve at one end of its stroke to thereby control the velocity of said helve.

2. A mechanical hammer comprising a housing, `an operating shaft reciprocably mounted in said housing, said shaft being spring-pressed in opposite directions, a sleeve reciprocably mounted in said housing, a helve reciprocably mounted in said sleeve and in alignment with said operating shaft, said helve being spring-pressed in opposite directions and constructed and arranged to contact the adjacent end of said operating shaft, means for reciprocating said Sleeve, and resilient means backed by said housing and providing yielding resistance for absorbing the impact of the helve near the end of its reciprocation in one direction to thereby control the velocity of said helve.

3. A mechanical hammer comprising a housing, an operating shaft reciprocably mounted in said housing, said shaft being spring-pressed in opposite directions, a helve reciprocably mounted in said housing and in alignment with said operating shaft, said helve being spring-pressed in opposite directions and constructed and arranged to contact the adjacent end of said o-perating shaft, means for reciprocating said helve, and resilient means backed by said housing and providing yielding resistance for absorbing unspent forces of the helve in one direction of its reciprocation which thereby assists in returning the helve.

4. A mechanical hammer comprising a housing, an operating shaft mounted for reciprocating movement in said housing, a helve reciprocably mounted in said housing and in alignment with said operating shaft, said helve being spring pressed in opposite directions and constructed and arranged to contact the adjacent end of said operating shaft, means for reciprocating said helve, and resilient means backed by said housing and providing yielding resistance for decelerating the movement of the helve at one end of its stroke to thereby control the velocity of said helve.

5. A mechanical hammer comprising a housing, an operating shaft'mounted for reciprocating movement in said housing, a sleeve reciprocably mounted in said housing, a helve reciprocably mounted in `said sleeve and in alignment with said operating shaft, said helve being spring pressed in opposite directions and constructed andarranged to contact the adjacent end of said operating shaft; means for reciprocating said sleeve, and resilient means backed by said housing and providing yielding resistance for absorbing the impact of the helve near the end of its reciprocation in one direction to thereby control the velocity of said helve.

6. A mechanical hammer comprising a housing, an operating shaft mounted for reciprocation in said housing, a helve reciprocably mounted in said housing and in alignment With said operating shaft, said helve being spring pressed in pposite directions and constructed and arranged to Contact the adjacent end of said operating shaft, means for reciprocating said helve, and resilient means backed by said housing and providing yielding resistance for absorbing unspent forces of the helve in one direction of its reciprocation which thereby assists in returning the helve.

7. In a mechanical hammer, a housing, a reciprocating sleeve within said housing, a hammer member having connection with said sleeve by means of resilient springs arranged so as to yieldingly oppose movement of said hammer member relative to the sleeve, and other yielding means comprising a coil spring located in the housing in alignment with the hammer member and providing resistance for controlling the velocity of said hammer member by absorbing the impact of the hammer member near the end of its reciprocation in one direction.

8. In a mechanical hammer, a housing, a reciprocating sleeve Within said housing, a hammer member having connection with said sleeve by means of springs arranged so as to yieldingly oppose relative movement of the hammer member with respect to the sleeve, whereby the travel of said hammer member will be greater than that of said sleeve, and a resilient coil spring located in the housing in alignment with the hammer member and providing yielding resistance for decelerating said hammer member at one end of its stroke, whereby the travel of the hammer member is controlled Without maintaining uniform reciprocating movement of said sleeve.

9. In a mechanical hammer, a housing, a sleeve mounted for reciprocating movement Within said housing, a helve having connection with said sleeve by means of springs arranged so as to yieldingly oppose relative movement between the helve and sleeve, means for reciprocating said sleeve to produce reciprocating movement of said helve imparted thereto through said springs, a tool shank slidable in said housing and adapted to receive blows from said helve, and a resilient coil spring backed by said housing and providing yielding resistance adapted to assist in restricting the reciprocating movement of the helve in that direction toward said tool shank.

10. In a mechanical hammer, a housing, a reciprocating sleeve Within said housing, a helve in said sleeve and connected therewith by means of springs arranged so as to yieldingly oppose relative movement of the helve with respect to the sleeve, means for reciprocating said sleeve,

11. A mechanical hammer comprising a housing, a helve mounted for reciprocating movement in said housing, means for reciprocating said helve,V said helve being spring pressed in opposite directions and arranged so that said reciprocating movement is:l imparted thereto through said springs, and resilient means backed by said housing and providingyielding resistance for decelerating the movement of said helve at one end of its stroke. v

FREDERICK B. MILLER. 

